1. Field of the Invention
The invention relates in general to a near-field communication (NFC) device and associated control method, and more particularly to an operation mode switching module for switching the NFC device among various operation modes and an associated method for achieving power-saving.
2. Description of the Related Art
Near-field communication (NFC) radio-frequency identification (RFID) is a technique allowing data exchange between two devices through sensing within centimeters without coming into physical contacts. Mifare specifications proposed by NXP spun off from Philips and FeliCa specifications proposed by Sony, as two prominent standards of NFC RFID, prevail in transportation and financial applications.
The current NFC technology is initiatively defined by an industrial organization called the NFC Forum. Various operation modes defined by the NFC forum include a reader/writer mode, a peer-to-peer mode and a card-emulation mode. When operating in the reader/writer mode, an NFC device, behaving as a common NFC reader at this point, reads data from or writes data to a conventional NFC card. When operating in the peer-to-peer mode, two NFC devices are allowed to exchange data. For example, two NFC devices may shared Bluetooth or WiFi configuration parameters or exchange digital images. When operating in the card-emulation mode, an NFC device functions as a conventional NFC card with respect to an external card reader. The care-emulation mode is commonly implemented in wireless ticketing or paying systems. Apart from the three modes above, an NFC device may also operate in a wireless communication based on another protocol, depending on an expected function of the NFC device.
Accompanied with the prevalence of the NFC technology, the NFC technology is also employed in mobile devices (such as personal digital assistants) to bring users with convenient operation experiences. For example, a smart handset utilizing the NFC technology (to be referred to as an NFC handset) is operable in the card-emulation mode to perform small-amount payments through wireless means, in the reader/writer mode to read advertisements carried in a smart poster, or in the peer-to-peer mode to share photos therein with another smart handset.
Among the NFC operation modes, the reader/writer mode and the peer-to-peer mode involve extremely power-consuming operations, whereas the card-emulation mode is a less power-consuming mode. Approaches for switching the operation mode is a critical factor on a standby period of a mobile device.
A common approach for switching the operation mode is by manual means. For example, an NFC handset is configured to the card-emulation mode under normal circumstances. Only when a user selects a specific application in the NFC handset, the NFC handset enters the reader/writer mode or the peer-to-peer mode. Such approach is quite power-saving yet inconvenient from an operation perspective for a user.
Another approach is implemented by means of polling. For example, an NFC handset mostly operates in the card-emulation mode, and periodically, temporarily and automatically enters the reader/writer mode. Thus, when a user carrying the NFC handset and approaches a smart poster, the NFC is capable of automatically reading information contained in the smart poster. However, although this approach yields preferred operation conveniences, the power consumed by the NFC handset each time the NFC handset enters and operates in the reader/writer mode is quite considerable to reach as high as 50 mA. Such power consumption is lethal on the standby period of a mobile device.
Therefore, there is a need for a solution for selecting and switching an operation mode for enhancing operation conveniences and at the same time prolonging a standby period of a mobile device.